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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Measurements of Man-Made Spectrum Noise Floor

This report consolidates research carried out at Clemson University and Stanford University where a series of measurements were undertaken to identify the man-made radiation present in four bands used by rather different services, namely, L1 Band (1563.42 1587.42 MHz), the Unified S-Band (2025 2110 MHz), the 2.4 GHz Industrial, Scientific and Medical (ISM) Band (2400 2482.50 MHz), and the 23.6-24.0 GHz Passive Sensing Band. Results show that there were distinctive differences in the measurement data in the frequency bands, which should be expected based on the function/regulation associated with each. The GPS L1 Band had little to none terrestrial man-made sources, but the ISM 2.4 GHz Band had a large number of man-made sources regardless of the site and the time. The Unified S Band showed mixed results depending on the sites. The Passive Sensing Band does not contain appreciable man-made radiation.

FROM↗
NASA NTRS2004

Controllable Curved Mirrors Made from Single-Layer EAP Films

A document proposes that lightweight, deployable, large-aperture, controllable curved mirrors made of reflectively coated thin electroactive-polymer (EAP) films be developed for use in spaceborne microwave and optical systems. In these mirrors, the EAP films would serve as both structures and actuators. EAPs that are potentially suitable for such use include piezoelectric, electrostrictive, ferroelectric, and dielectric polymers. These materials exhibit strains proportional to the squares of applied electric fields. Utilizing this phenomenon, a curved mirror according to the proposal could be made from a flat film, upon which a nonuniform electrostatic potential (decreasing from the center toward the edge) would be imposed to obtain a required curvature. The effect would be analogous to that of an old-fashioned metalworking practice in which a flat metal sheet is made into a bowl by hammering it repeatedly, the frequency of hammer blows decreasing with distance from the center. In operation, the nonuniform electrostatic potential could be imposed by use of an electron gun. Calculations have shown that by use of a single- layer film made of a currently available EAP, it would be possible to control the focal length of a 2-m-diameter mirror from infinity to 1.25 m.

Bao, Xiaoqi↗
NASA NTRS1961

ON THE ACCURACY OF MEASUREMENTS MADE UPON FILMS PHOTOGRAPHED BY BAKER-NUNN SATELLITE TRACKING CAMERAS

The photographs taken by the Baker-Nunn cameras of the Smithsonian Astrophysical Observatory were formerly measured with Van Biesbroeck goniometers, but are now measured exclusively with Mann two-screw comparators. Instead of measuring point images, we usually have to measure oblong images, either trails or breaks (the latter produced by interruption of the exposure). We can therefore expect that the accuracy of the determination of their positions is more influenced by the personal errors than it is in conventional astrometry. Approximately 800 measurements were made on 34 images of different length, and, from these, the frequency distribution of settings was determined. Then the relationship between this distribution and the length of the image (trail or break) was examined, and the relationship between the "magnitude error" and the length of image was determined. Measurements were made at different angles formed by the trails and the reticle lines, and it was found that the accuracy was not affected by the angle of the setting. Position determinations have been made using reference stars at different distances. On the basis of these results, we can conclude that the accuracy is neither influenced by the distortion of the emulsion nor by the optical distortion within an area of a diameter of S cm (5°.8). We believe that we are justified in using the linear plate constant method, at least within this area. From numerous double and multiple measurements, the following standard errors were determined for a single position.

ASTROMETRY↗
NASA NTRS1982

Tribological evaluation of composite materials made from a partially fluorinated polyimide

Preliminary tribological studies on a new polyimide formulated from the diamine 2,2-bis 4-(4-aminophenoxy) phenyl hexafluoropane (4-BDAF) indicates polyimides made from this diamine have excellent potential for high temperature applications. Two different polyimides were formulated from the diamine, and five different composites were formulated using one of the polyimides. Composites were made using 10 weight percent (w/o) graphite fluoride powder, 20 w/o PTFE powder, 30 w/o silver powder, or 50 w/o carbon fibers, both graphitic and nongraphitic types. The powder additions did not improve the tribological properties as much as the carbon fibers, and the graphitic fibers produced better results than did the nongraphitic fibers. Results also indicated that improved high temperature stability and tribological properties may be obtained with a polyimide made from the dianhydride pyromellitic acid (PMDA) rather than the dianhydride benzophenonetetracarboxylic acid (BTDA).

Fusaro, R. L.↗
NASA NTRS1982

Evaluation of SRB phenolic TPS material made by an alternate vendor

Tests conducted to evaluate the adequacy of solid rocket booster (SRB) phenolic thermal protection system (TPS) material supplied by an alternate vendor chosen by United Space Boosters, Inc. (USBI), to replace the current phenolic TPS sections used thus far on the first four Shuttle flights. The phenolic TPS is applied mainly to the attach and kick rings of the solid rocket booster (SRB). Full-scale sectional models of both the attach and kick ring structure were made up with 0.0265 in. thick stainless steel thin skin covers with thermocouples on them to determine the heating rates. Such models were made up for both the forward and rear faces of the kick ring which has a different configuration on each side. The thin skins were replaced with the alternate phenolic TPS sections cut from flight hardware configuration phenolic parts as supplied by the new vendor. Two tests were performed for each configuration of the attach and kick rings and the samples were exposed to the flow for a duration that gave a heat load equivalent to that obtained in the series of runs made for the current line of phenolic TPS. The samples performed very well with no loss of any phenolic layers. The post-test samples looked better than those used to verify the current phenolic TPS.

Karu, Z. S.↗
NASA NTRS1988

Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 2: Rectangular planform blades at an advance ratio of 0.23

An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (mu sub infinity = 0.23). The measurements were made with a two-component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 180 separate locations in order to clearly define the inflow character. This data is presented without analysis.

Elliott, Joe W.↗
NASA NTRS1988

Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 3: Rectangular planform blades at an advance ratio of 0.30

An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (micron sub infinity = 0.30). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 180 separate locations in order to clearly define the inflow character. These data are presented without analysis.

Elliott, Joe W.↗
NASA NTRS1988

Inflow measurements made with a laser velocimeter on a helicopter model in forward flight. Volume 4: Tapered planform blades at an advance ratio of 0.15

An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into the scale model helicopter rotor in forward flight (mu sub infinity = 0.15). The measurements were made with a two-component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 146 separate locations in order to clearly define the inflow character. This data is presented herein without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in MS-DOS format.

Althoff, Susan L.↗
NASA NTRS1988

Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 5: Tapered planform blades at an advance ratio of 0.23

An experimental investigation was conducted in the 14- by 22-Foot Subsonic tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (mu sub inf = 0.23). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the blade tips. A conditional sampling technique was employed to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 168 separate locations in order to clearly define the inflow character. This data is presented without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependenet values are included as part of this report on two 5.25 inch floppy disks in Microsoft Corporation MS-DOS format.

Althoff, Susan L.↗
NASA NTRS1988

Inflow Measurements Made with a Laser Velocimeter on a Helicopter Model in Forward Flight. Volume 1: Rectangular Planform Blades at an Advance Ration of 0.15

An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley to measure the inflow into a scale model helicopter rotor in forward flight (microinf = 0.15). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 147 separate locations in order to clearly define the inflow character. This data is presented without analysis. In order to increase the availability of the resulting data, both the mean and azimuthally dependent values are included as part of this report on two 5.25 inch floppy disks in Microsoft Corporation MS-DOS format.

Elliott, Joe W.↗
NASA NTRS1993

Cirrus microphysics observations made during FIRE 2: Small particles, high concentrations, and probe comparisons

Aircraft observations of cirrus cloud microphysics were made near Coffeyville, Kansas during Nov. and Dec. 1991. Cloud microphysics measurements were made using both a PMS 2DC probe and an ice particle replicator, both were mounted on the UND Citation aircraft. Intercomparison is made of the size, area, and ice mass spectra determined from these probes. The PMS 2DC undercounts particles for D less than 70 microns and the replicator oversizes particles for D greater than 150 microns, at least when column rosettes are encountered. High concentrations of particles with D less than 50 microns are noted in selected portions of the 22 Nov. 91 replicator data set. Relations between the maximum dimension of a crystal and its shadow area (known as area dimensional relationships) are computed from the PMS data. Area and mass dimensional relationships are used to give a simple analytical expression for computing the wavelength dependent absorption coefficient averaged over a size bin. Calculations based upon the replicator data show that crystals with D less than 50 microns contribute significantly to the solar extinction and infrared absorption coefficients during some time intervals.

Arnott, W. P.↗
NASA NTRS1994

Results of time-resolved radiation exposure measurements made during U.S. shuttle missions with a tissue equivalent proportional counter

Time resolved exposure measurements inside the crew compartment have been made during recent shuttle missions with the USAF Radiation Monitoring Equipment-III (RME-III), a portable four-channel tissue equivalent proportional counter. Results from the first six missions are presented and discussed. The missions had orbital inclinations ranging from 28 degrees to 57 degrees, and altitudes from 200-600km. Dose equivalent rates ranged from 40-5300 micro Sv/dy. The RME-III measurements are in good agreement with other dosimetry measurements made aboard the vehicle. Measurements indicate that medium- and high- Linear Energy Transfer (LET) particles contribute less than 2% of the particle fluence for all missions, but up to 50% of the dose equivalent, depending on the spacecraft's altitude and orbital inclination. Isa-dose rate contours have been developed from measurements made during the ST-28 mission. The drift rate of the South Atlantic Anomaly (SAA) is estimated to be 0.49 degrees W/yr and 0.12 degrees N/yr. The calculated trapped proton and Galactic Cosmic Radiation (GCR) dose for the STS-28 mission were significantly lower than the measured values.

Golightly, M. J.↗
NASA NTRS1995

Polyimides Made From PDMDA

Thermally stable linear aromatic polyimides with improved optical, electrical, and processing characteristics made from 3,3'-bis(3,4-dicarboxyphenoxy)diphenylmethane dianhydride (PDMDA). Made in form of powders that can be dissolved to cast thin films. Potentially useful as coating and matrix materials. Films made vary from transparent to pale yellow. Greater degrees of transparency and lower dielectric constants make these polyimides more suitable for use in some electronic and optical applications; e.g., as insulating materials on wires and protective films on solar photovoltaic cells.

St. Clair, Anne K.↗
NASA NTRS2012

Airborne Measurements of Atmospheric Pressure made Using an IPDA Lidar Operating in the Oxygen A-Band

We report airborne measurements of atmospheric pressure made using an integrated path differential absorption (IPDA) lidar that operates in the oxygen A-band near 765 nm. Remote measurements of atmospheric temperature and pressure are needed for NASA s Active Sensing of CO2 Emissions Over Nights, Days, and Seasons (ASCENDS) mission to measure atmospheric CO2. Accurate measurements of tropospheric CO2 on a global scale are very important in order to better understand its sources and sinks and to improve our predictions of climate change. The goal of ASCENDS is to determine the CO2 dry mixing ratio with lidar measurements from space at a level of ~1 ppm. Analysis to date shows that with current weather models, measurements of both the CO2 column density and the column density of dry air are needed. Since O2 is a stable molecule that uniformly mixed in the atmosphere, measuring O2 absorption in the atmosphere can be used to infer the dry air density. We have developed an airborne (IPDA) lidar for Oxygen, with support from the NASA ESTO IIP program. Our lidar uses DFB-based seed laser diodes, a pulsed modulator, a fiber laser amplifier, and a non-linear crystal to generate wavelength tunable 765 nm laser pulses with a few uJ/pulse energy. The laser pulse rate is 10 KHz, and average transmitted laser power is ~20 mW. Our lidar steps laser pulses across a selected line O2 doublet near 764.7 nm in the Oxygen A-band. The direct detection lidar receiver uses a 20 cm diameter telescope, a Si APD detector in Geiger mode, and a multi-channel scalar to detect and record the time resolved laser backscatter in 40 separate wavelength channels. Subsequent analysis is used to estimate the transmission line shape of the doublet for the laser pulses reflected from the ground. Ground based data analysis allows averaging from 1 to 60 seconds to increase SNR in the transmission line shape of the doublet. Our retrieval algorithm fits the expected O2 lineshapes against the measurements and determines the atmospheric pressure by minimizing the error between the observations and model. We first demonstrated our airborne lidar during flights during summer 2010. We made several improvements and made measurements during the Ascends flights during July 2011. More information about the technique, lidar instrument, airborne measurements, and pressure estimates will be described in the presentation.

Riris, Haris↗
NASA NTRS2018

The Gaia Catalogue Second Data Release and Its Implications to Optical Observations of Man-Made Earth Orbiting Objects

The Gaia catalogue second data release and its implications to optical observations of man-made Earth orbiting objects. Abstract and not the Final Paper is attached. The Gaia spacecraft was launched in December 2013 by the European Space Agency to produce a three-dimensional, dynamic map of objects within the Milky Way. Gaia's first year of data was released in September 2016. Common sources from the first data release have been combined with the Tycho-2 catalogue to provide a 5 parameter astrometric solution for approximately 2 million stars. The second Gaia data release is scheduled to come out in April 2018 and is expected to provide astrometry and photometry for more than 1 billion stars, a subset of which with a the full 6 parameter astrometric solution (adding radial velocity) and positional accuracy better than 0.002 arcsec (2 mas). In addition to precise astrometry, a unique opportunity exists with the Gaia catalogue in its production of accurate, broadband photometry using the Gaia G filter. In the past, clear filters have been used by various groups to maximize likelihood of detection of dim man-made objects but these data were very difficult to calibrate. With the second release of the Gaia catalogue, a ground based system utilizing the G band filter will have access to 1.5 billion all-sky calibration sources down to an accuracy of 0.02 magnitudes or better. In this talk, we will discuss the advantages and practicalities of implementing the Gaia filters and catalogue into data pipelines designed for optical observations of man-made objects.

Frith, James M.↗
NASA NTRSDate not supplied

NASA’s Space Launch System Stands Ready on Doorstep of Maiden Voyage Launch and Progress Made to Future Missions

NASA and its partners made significant progress towards the Artemis I launch in 2022. The integrated Space Launch System (SLS)vehicleand Orion spacecraft were first rolled out of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center (KSC) in March. SLS is a super heavy-lift vehicle to send large, strategic payloads to the Moon, Mars, and beyond. It isthebackbone of the Artemis human lunar exploration program. Rollout transported the vehicle to Launch Pad 39B for a series of tests, including the wet dress rehearsal (WDR). Multiple attempts were required to complete WDR, each building on the one before. Following the WDR campaign, NASA teams refined hardware and launch procedures, and the vehicle was prepared for its first launch attempt scheduled for August 29. Challenges with the weather and hardware resulted in a scrub on the 29th, and the second attempt was set for Sept. 3. A hydrogen leak on the tail service mast umbilical forced a scrub. NASA teams completed repairs and testing on the vehicle on Launch Pad 39B to preserve a launch attempt at the end of September. Managers chose to return the vehicle to the VAB to protect it fromthe threat of Hurricane Ian. Within the VAB, NASA further inspected and prepared SLS for selected November windows. In addition to progress to the Artemis I mission, significant progress was made on the Artemis II and Artemis III rockets. Progress was also made towards on the Block 1B and Block 2 variants, beginning on the fourth and ninth flight, respectively. Both variants will provide significant improvements in both launch mass and mission flexibility to multiple destinations. This paper will discuss Artemis I vehicle integration, testing, and available results from the launch campaign to date.

Bruce Askins↗
NASA NTRS1974

AAFE man-made noise experiment project. Volume 1: Introduction experiment definition and requirements

An experiment was conducted to measure and map the man-made radio frequency emanations which exist at earth orbital altitudes. The major objectives of the program are to develop a complete conceptual experiment and developmental hardware for the collection and processing of data required to produce meaningful statistics on man-made noise level variations as functions of time, frequency, and geographic location. A wide dispersion measurement receiver mounted in a spacecraft operating in a specialized orbit is used to obtain the data. A summary of the experiment designs goals and constraints is provided. The recommended orbit for the spacecraft is defined. The characteristics of the receiver and the antennas are analyzed.

Source record↗
NASA NTRS1974

AAFE man-made noise experiment project. Volume 2: Project and experiment discussions

An experiment for the acquisition and processing of man-made noise interference data on earth orbital altitudes is discussed. The objectives of the project are to confirm the results of analytical studies concerning radio frequency man-made noise in space. It is stated that the measurements of the amounts and types of noise in frequency bands of interest could allow the allocation and utilization of frequencies to be optimized and would also contribute to the engineering objective of optimizing flight receiving systems. A second objective of the project was to design and fabricate a noise measuring receiver which would demonstrate the feasibility of the experiment design under the project. The procedures for acquiring and processing the electromagnetic radiation data are discussed.

Source record↗